Human papillomavirus (HPV) has been studied extensively as a precursor of invasive cervical cancer and cervical intraepithelial neoplasia. Cervical cancer is the second most common cancer worldwide, and is the most common malignancy in developing countries.
Cervical cancer screening is commonly based on cytological and colposcopic analyses. The generally accepted cytological smear of the cervix (Papanicolaou test, Pap smear) has led to a reduction in the incidence of and mortality caused by cervical cancer. However, there are certain disadvantages to using the Pap smear test. One of the limitations of the conventional Pap smear includes non-representative transfer of cells. Also, due to obscuring of the abnormal cells by debris, such conventional methods can lead to an increase in false-negatives and equivocal results.
All forms of the Pap test focus on the screening for high-grade precursor lesions so that treatment can be initiated before these precursors progress into invasive cancers. To effectively differentiate and communicate the presence of cytologically and biologically distinctive grades of preneoplastic and cancerous lesions, the Bethesda System for Reporting Cervical Cytology has recommended six categories to characterize squamous cell abnormalities. The six categories include: (1) atypical squamous cell of undetermined significance (ASCUS), (2) atypical squamous cells, cannot exclude high-grade squamous lesions (ASC-H), (3) low-grade squamous intraepithelial lesions (LSIL), (4) high-grade squamous intraepithelial lesions (HSIL), (5) squamous cell carcinoma (SCC) and (6) normal. Under this system, HSIL may optionally be subcategorized as “HSIL (moderate dysplasia, CIN II)” or “HSIL (severe dysplasia, CIN III)”. Colposcopy, and possible biopsy have been recommended as a follow-up test for ASC-H, LSIL, HSIL, and SCC, while HPV testing has been recommended for ASCUS.